Join Date: Feb 2000
Location: Annapolis, Md
Thanked 215 Times in 166 Posts
Rep Power: 10
As has been said, very few boats can withstand a full speed collision with an immovable object such as a rock. I apologize that I had written this for an earlier discussion on this topic and so it may not be completely relevant.
With a bolt-on keel, the good news is that if the boat does not sink, a nearly good as new repair can usually be made. The bad news is that this can often involve removing the keel, cutting away all damaged glass (which may include the internal framing as well, doing a careful rebuild. It is rare that the bolts themselves fail and when they do, it is usually a case where corrosion has badly reduced the diameter of the bolt.
Lead keels are generally considered better the cast iron in these types of collisions because the lead can absorb some of the shock and therefore impart less force into the hull and keel attachment structure.
This kind of full speed impact with the proverbial immovable object is especially devastating to most encapsulated keels. In a full speed collision, the fiberglass itself comes into contact with the object and is generally crushed and deformed. This allows the ballast keel to be pushed upward into the bilge membrane. Unlike most bolt on keels, encapsulated keels rarely have the internal structure to absorb and distribute these impact forces.
Successfully rebuilding this kind of damage is much more difficult. The ballast should be removed, the encapsulation envelope checked for internal damage, and repaired, the ballast bonded back in place, and the internal bilge membrane rebuilt. It is very hard to get this back to being a like-new repair.
Owners and insurance companies often elect to merely repair the point of contact on the encapsulation envelope. That often is not an adequate repair. The bond between the ballast keel and the keel envelope, is a part of the structure of the boat. It allows the load of the ballast to transfer and be distributed into the hull, and is the reason that encapsulated keels often get by with minimal internal framing. In the kind of grounding being discussed, that bond between ballast keel and the shell is generally broken resulting in a boat with substantially less resistance to the next hard grounding, with a greater tendency for blisters due to moisture trapped in the encapsulation, and greater tendency toward flexure and therefore fatigue.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay